The absolutely vital question was whether the Government had power to control them at all.

This question had not yet been decided in favor of the United States Government.

It was useless to discuss methods of controlling big business by the National Government until it was definitely settled that the National Government had the power to control it.

A decision of the Supreme Court had, with seeming definiteness, settled that the National Government had not the power.
This decision I caused to be annulled by the court that had rendered it; and the present power of the National Government to deal effectively with the trusts is due solely to the success of the Administration in securing this reversal of its former decision by the Supreme Court.
The Constitution was formed very largely because it had become imperative to give to some central authority the power to regulate and control interstate commerce.

At that time when corporations were in their infancy and big combinations unknown, there was no difficulty in exercising the power granted.